1. Field of the Invention
The present invention relates to an automatic light switching system of the type primarily intended for use in operating an electrical light circuit. By virtue of the construction of the light switching system, lights, or other work loads electrically connected to the circuit to be operated, may be energized in a predetermined fashion in response to signals from an automatic timer.
2. Description of the Prior Art
Various forms of and constructions for automatic timers utilized to operate electrical appliances are well known in the prior art. Briefly stated, these timing devices comprise electric clock, or timer, circuits energized by 115 volt AC current from a wall outlet. The timer is plugged into the outlet and on-off sequences are set by a dial on the timer's face. The timer then further includes an outlet where the electrical cord of some appliance, such as a coffee pot or a light, is inserted. Then, dependent upon the setting on the timer's dial, a circuit within the timer opens and closes to allow current to flow through the timer's outlet into the appliance. Generally speaking, it may be said that two embodiments of such timers are available on the market today. One timer is sold under the mark General Electric, and a second type is sold under the mark Intermatic. The distinctions between the two types of timers are primarily a matter of internal wiring and not of ultimate function.
However, as is apparent from the description in the preceding paragraph, these timers are utilized to regulate the on-off condition of some external appliance. That is to say, the timers do not regulate the flow of current through the circuit into which they are inserted, and from which the timer receives its operating current. While this is of no real concern with regard to the operation of a coffee pot, it is apparent that there is a great need for some means of controlling an existing electrical circuit such as a home's external lights.
In recognition of this need there are prior art devices which are capable of controlling in a timed fashion, an electrical circuit. One immediate solution to the problem is the installation of a timing control as the actual switch means for the circuit. However, not only might this eliminate the use of the circuit except by the timing device, it must also be built into the circuit. This necessarily increases the cost of such a device and effectively restricts its utility to new installations.
Another solution is illustrated in U.S. Pat. No. 3,889,132 to Vreeland. That patent teaches a construction for a timer assembly comprising a specifically constructed plug casing including a timer to be used in combination with a modified wall receptacle. Though quite suitable for its intended purpose, the Vreeland device is somewhat limited by the fact that a special plug casing/timer must be utilized.
Accordingly, it is clear that there is a great need in the art for an automatic switching system which is easily adaptable for use in existing electrical circuits. Such a system would require only minor modification of the circuit to be operated and would, preferably, utilize as the timing mechanism a commercially-available timer device. Such a system would not only be relatively inexpensive to install, but would also provide great flexibility of use.